Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/116

 104 is of a bluish colour and a crystalline grain; it is here also frequently intersected by veins of calcareous spar. The cliffs near Stonehouse being much exposed to the action of the sea, afford very distinct proofs of its effect on the most tender parts of the rock. It has made in several places erosions or crevices of various extent, which have been afterwards filled by a gravelly sand thrown up by the sea, and which has, by drying, become so coherent, that one might be led into error, by conceiving that the sand alternates in beds with the limestone.

But it is at the eastern end of the Flying bridge, on the left bank of the Plym, that the transition limestone is found in its true character. I have no where seen it so well characterized, not even at Meillerie in Savoy, on the borders of the Lake of Geneva. The strata have the same direction and the same degree of inclination as those at Catwater. There is a quarry belonging to Lord Borringdon, which is an excellent spot for studying it. This limestone is blackish-brown, several rhomboidal plates of calcareous spar may be seen disseminated through the mass, and it suddenly assumes in the same stratum, all the characters of a shining slate; the rock in this last state effervesces less briskly with acids.

On quitting the coast, and advancing into the interior of the country, there is seen on the road from Saltram to Plymptom Earle a slaty amygdaloid, the base of which is of a purplish-brown colour, the nodules calcareous, and the greater part of them very minute. I found in the same neighbourhood, on the surface of the fields, in adventitious blocks and pebbles, another species of amygdaloid, the base of which is greenish-grey, and has the lustre of satin; several of the nodules being completely decomposed, had left corresponding empty spaces.

I cannot say what formation is found on the shore to the east of